<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style type="text/css">
        .con{
            width: 400px;
            height: 400px;
            border: 1px solid #000;
            margin: 50 auto 0;
        }
        .box01,.box02{
            width: 300px;
            height: 100px;
            margin: 10px;
        }
        
        .box01{
            background-color: green;
            position: relative;
            left: 50px;
            top: 50px;
        }
        .box02{
            background-color: gold;
        }

    </style>
</head>
<body>
    <div class="con">
        <div class="box"></div>
        <div class="box01"></div>
        <div class="box02"></div>
    </div>
</body>
</html>